Armor plate, looking for info

[Tororider]

So in an effort to have a bullet trap that won't weigh hundreds of pounds, I have looked into armor plate. There is a place nearby that plates vehicles and has "scraps" that they are selling for $20 a square foot. It is 3/8" bradley armor plate 40100. The 40100 means nothing to me, but I know nothing about armor plate. Will this armor plate be strong enough to shoot thousands of rounds at it when it is angled at 45 degrees? Also, what caliber would it be safe up to? Thanks for any help.

 

[jwstewar]

Would the 45 degree angle just cause the bullet to richochet? I have no clue, just my guess.

 

[Tororider]

Thats how you use a bullet trap. The 45 degree angle deflects the bullet into the ground or sand tray. I am just wondering the strength of the specific type of armor plate vs. steel plate, like 1/2" or 1".

 

[SPYDERLK]

AR 400 and AR 500 are normally used. Im not sure about the #s you listed. Regular cold or hot rolled steel lacks strength and abrasion resistance. Thats the "AR". Google it a bit.
larry

 

[Tororider]

I just talked to the guy, he said it is 46100 not 40100. I think I found some info on that yesterday while googling so I will see what I can found. He also said it has a brinell hardness rating of between 477 and 524.

 

[SPYDERLK]

That is about the same as AR 500 surface hardness then. As I understand it the ARs are not thru hardened. The hard surface gives the abrasion resistance needed. I think your quoted steels will be superior with the implication that they are thru hardened. The price sounds like a good deal.
larrt

 

[LD1]

The bullet trap that we have used for years is just two 3' x 3' 1/4" plate welded together to make it 1/2" overal thickness. It stands on a 45 and has been shot hundreds of time with .22-250 bullets cooking at 3800fps.

It definatally craters out the steel and demples the backside.

Not sure what effects a larger caliber might have like a .308 or .30-06. It might punch through or the heavier, larger diameter, slower bullet might deflect even better.

There are some places where multiple rounds have hit the exact same spot several times and you can just start to see a little daylight through. But I live way out in the sticks with no worries at all, the only reason we us it is because it's easy to hang targets up, just grab a magnet.

I would say a similar design would be perfect for any handgun and smaller rifle rounds like 22long and 22wmr, on up from that it becomes questionable.

 

[MikeD74T]

Thickness & material strength requirements should be somewhat proportional to the angle of impact ??? How much more would it cost to reduce the angle of impact to 30 or even 15 degrees? i.e. longer plate mounted flatter
Also how about a layer of hardened material backed up with cold rolled? MikeD74T

 

[jimg]

AR 400 and AR 500 are normally used. Im not sure about the #s you listed. Regular cold or hot rolled steel lacks strength and abrasion resistance. Thats the "AR". Google it a bit.
larry

This. Can only add ar500 is also highly impact resistant in addition to abrasion resistant. Ive built swingers and traps out of 3/8" ar500 and its plenty tough. Ive shot them w/ everything from .22lr to .458 Lott and never had a problem. In fact it doesnt noticeably dent. I bought my stock from the local steel yard as 'drops' which made the entire affair much less expensive. Be certain to check w/ the steel makers recommendations prior to welding/cutting. In my case they recommended a preheat prior to welding + required low H rods.

 

[JoeL4330]

you may wish to add a few sheets of Kevlar or equivalent, anchored at the top only ...free to swing

 

[Erik_in_Hoyt]

.308 and 30-06 fmj will drill through 1/2" hot rolled steel.
they will crater 5/8" "tool surface" hardened 4140.
angling your backstop does 2 things: first it increases the cross sectional thickness of the material - which means you can use lighter gauge steel to give an equivalent stopping power as a thicker piece (so at 45 degrees slant, .375" plate will react to the bullet as if it is .5375" thick). Second, putting the steel at an angle to begin with helps "aim" the ricochet, thus lessening your chances of getting hit with a bounce-back.

Hardening the steel makes it more resistant to dimpling or cratering -- which helps keep the ricochet pattern predictable.

 

[SPYDERLK]

.308 and 30-06 fmj will drill through 1/2" hot rolled steel.
they will crater 5/8" "tool surface" hardened 4140.
angling your backstop does 2 things: first it increases the cross sectional thickness of the material - which means you can use lighter gauge steel to give an equivalent stopping power as a thicker piece (so at 45 degrees slant, .375" plate will react to the bullet as if it is .5375" thick). Second, putting the steel at an angle to begin with helps "aim" the ricochet, thus lessening your chances of getting hit with a bounce-back.

Hardening the steel makes it more resistant to dimpling or cratering -- which helps keep the ricochet pattern predictable.

Angling does a third thing that is very important... it deflects, rather than stopping the bullet. Much less energy is absorbed by the plate.
larry

 

[xlr82v2]

I used to shoot IHMSA handgun silhouette, and built a set of swinger targets about 15 years ago from AR400.

As long as you keep your impact velocities down below 2300 fps, the bullets won't penetrate the steel... get much above that, and you'll start to see the bullets crater the steel. The higher the impact velocity, the deeper the crater. Caliber has nothing at all to do with cratering... It's all about impact velocity (Of course, this is limited to non-armor piercing, hunting or target bullets from .224 to .430 caliber... all bets are off if you throw some military AP stuff at it).

Have fun!

 

[Wis Bang]

I helped demo a two lane 'police' practice range in the basement of City hall that was built for pistol practice & qualification.

Each lane had a 4X8X1/2" sheet of plate w/ the bottom on the floor against the back wall and a 1/2" X 6" angle turned to resemble a sideways V supported the top. an additional 2" wide flat section spanned the center seam and each edge. The sandbox was only about 2.5 feet deep so the angle was alot steeper than 45 degrees.

There was a boxed I beam a few feet to the front that kept high shots from going over. The walls were 2" plaster over brick built in the early 20's w/ no additional protection for stray shots!

After tearing down the interior wall I can see why sledge hammers just bounced off & we had to borrow some 'shorti' 45LB jackhammers from the water dept & hold them across our chests & let them hammer away to get the bricks apart...they city was doing this on the cheap using 3 college kids on winter break @ min wage [early 70's a whopping $@.50/hr!] as they had spent millions on the new police facility behind city hall.

The holding cells were behind the backstop...prisoners had little to fear...

It was hard plate 'cause after 50 years of use w/ .38s the main impact area was only scarred a little! My father used to shoot w/ them and they used mostly lead wadcutters.

 

[2manyrocks]

The holding cells were behind the backstop...prisoners had little to fear...



Did they have many repeat offenders?

 

[Podunkadunk]

Brinell 500 is equivalent to Rockwell 52 on the hardness scale. Either are outstanding for what you're looking for.